During your child’s first few years, miraculous things happen. Your baby is growing at lightning speed right before your eyes (tripling her birth weight and height in 12 months), all the while developing skills she’ll use for the rest of her life. The development of these skills is measured by a series of milestones, from first steps to first words to first crayon scribbles (in a coloring book, if you’re really lucky). “Milestones are significant measures of a child’s development,” says Sean Cahill, MD, an assistant professor of pediatrics and internal medicine at Loyola University School of Medicine in Chicago. “The rate at which they happen varies from child to child, but the order is invariable.” Meaning your child will crawl (or roll or scoot) before she walks and blurt single words like “mama” before she can put sentences together.

Experts tend to break down children’s development into clinical-sounding categories like gross motor, fine motor, sensory, language and social skills. But we like the approach of Alan Greene, MD (aka “Dr. Greene”), a clinical professor of pediatrics at the Stanford University School of Medicine, who defines your child’s developmental areas like this:

Poet: The development of language and other forms of communication such as pointing at objects or relating to others.

Athlete: The development of the big muscle groups, including controlling the head, rolling over, sitting up and walking.

Scholar: The discovery of how the world works. When a child starts paying attention to where your eyes are focused rather than to your eyes themselves, or when he starts to reach for a toy that’s just beyond arm’s length, he’s developing his “scholar” skills.

Apprentice: The ability to grasp a toy, a spoon and, at about 1 year old, a single Cheerio.

You may not know whether you have a budding poet or a promising athlete in your home until your child is a lot older (perhaps even an adult!). Pediatricians hesitate to put a precise timeline on developmental milestones because the timing varies from child to child, but there are some markers they look for at certain ages. Here’s a general idea of what you can expect to see at 6 months, 12 months and up to 24 months, when your baby will no longer be a baby.

0–12 Months

This will be the most jam-packed year of your child’s life, developmentally speaking. Giant leaps in cognitive and physical skills are made literally every day, so you’ll want to keep your video camera within arm’s reach whenever possible.

The poet communicates. Even if your baby hasn’t pronounced one word by 12 months, it doesn’t mean she’s not “speaking.” “Crying, smiling, babbling are all important preverbal communication skills because they are precursors to verbal skills,” explains Suzanne Bonifert, MS, CCC/SLP, head of speech-language pathology at the University of Texas at Dallas Callier Center for Communication Disorders. Laughing at 2 to 4 months transitions vocal play (vowel sounds) at 4-6 months. Shortly afterward you’ll hear the consonant-vowel combinations (“baba”), and by 10 months you’ll likely notice sequences of syllables and sounds that seem as if your baby is trying to say a sentence or ask a question but it’s coming out as gobbledygook. “Typically, first words are spoken between 12 and 16 months,” says Bonifert.

The athlete rocks and rolls. These big-muscle motor skills are the easiest for parents—and doctors—to assess. From swiping at dangling toys at 3 months, a baby will progress to rolling over (and perhaps over and over) and sitting tripod-style by 6 months. Watch out, mom: By 12 months, your once quietly portable little darling will be transporting himself all over his universe via crawling, cruising or, quite possibly, walking all on his own.

The scholar reflects. Even at three months, your infant may smile at the sound of your voice because he now recognizes familiar people and objects. By seven months, he’ll play peek-a-boo, respond to your emotional expressions (whether it be joy or stress), struggle to get to an out-of-reach toy and love his own reflection in the mirror. “By 1 year, he’ll know the dog’s name, his sibling’s name and he’ll understand directions like ‘Come here,’” says Deb Lonzer, MD, the chair of community pediatrics for the Cleveland Clinic Pediatric Institute and Children’s Hospital in Ohio. “Of course, he’ll also be able to say no or shake his head when you do ask him to do something.”

The apprentice takes hold. As a child’s hand-eye coordination improves during this first year, you’ll see your child evolve from grasping a rattle at 3 months to transferring that rattle from hand to hand at 7 months. At 1 year, the pincer grasp (thumb and forefinger) will be so advanced she’ll be able to stuff her little mouth Cheerio by Cheerio. “Gradually, a child gets more precise—and pretty soon she’ll be ready for neurosurgery,” quips Greene.